1. Field of the Invention
The present invention relates to a treading fitness trainer, and more particularly, to a device which insures the coupling relationship between the handgrip connecting rod and the pedal connecting rod so that the pivoted elements cannot be loosened.
2. Description of the Prior Art
The prior art of U.S. Pat. 5,518,470 (an expansion invention of the prior art of U.S. Pat. 5,575,739), as shown in FIGS. 4 and 5, includes at least one resistance device 14 between a handgrip connecting rod 10 and a pedal connecting rod 12, wherein the motion of the human limbs (as shown in FIG. 5) can be simulated to achieve exercise. The resistance device 14 has an extendable shaft 16 and is coupled between the handgrip connecting rod 10 and the pedal connecting rod 12.
The pivoted connection elements 18 of the resistance device 14 will be easily loosened since they are directly forced by the motion of the handgrip connecting rod 10 and the pedal connecting rod 12. Accordingly, the users often encounter a slight play during the initial motion and the pivoted connection elements 18 must be frequently inspected and secured if they are loosened.